US-P18.179ab ।US-P18.179cd ॥
In plain words
When the meaning of the word 'thou' is not clearly distinguished in sentences like 'That thou art', the true import of the sentence—the direct realization that 'I am eternally free'—fails to shine forth.
Close to the Sanskrit
In sentences like 'That thou art', due to the non-discrimination of the meaning of the word 'thou', the sentence-meaning 'I am eternally free' is not manifested at all hence.